Cellular studies of learning and memory, and synaptic transmission are significantly hampered by standard optical configurations that were developed decades ago. This is especially true when considering present day, fluorescence microscope technology where a single optical input pathway provides wide-field illumination. For example, the integration of ion imaging with UV photolysis is compromised since focal UV excitation must be forced into the optical pathway that was designed only for epi-fluorescence illumination. The goal of this project is to test the feasibility of developing a twin-illumination pathway for fluorescencemicroscopes to allow the versatility necessary for the experiments of today and tomorrow. We will: 1) Design and build a twin-illumination pathway that will integrate with present day upright microscopes. 2) Test the optical properties of each illumination pathway for flatness of field, full-field illumination and light transmission properties. 3) Determine the reliability of motor control for positioning apertures and a UV transmitting optical fiber coupling mechanism in one of the illumination pathways. 4) Test and evaluate the feasibility of using "pass through optics to monitor the location of laser illumination beams for photolysis. 5) Test the twin-illumination system in photolysis experiments and in studies to monitor fast calcium transients. PROPOSED COMMERCIAL APPLICATION: This twin-IIumination system has many potential applications in science: simultaneous imaging together with focal ablation or photolysis, and by including apertures in one arm of the excitation pathway, it will be possible to use one pathway for restricted field excitation for measurement of fast changes in calcium in neuronal processes.